1. Field of the Invention
The present invention relates to a method for producing hydrogen halide and oxygen and, more particularly, the present invention relates to a method for producing hydrogen halide and oxygen comprising chemically reacting water and a halogen using porous silica as a catalyst.
2. Description of the Related Art
Because hydrogen and oxygen are attracting attention as clean sources of energy, a method by which water is broken down electrochemically has been established for their production on an industrial scale. However, this method has problems in terms of cost since it requires a large amount of electrical power. In order to solve this problem, a method has been proposed for chemically decomposing water.
Namely, water is reacted with halogen to form hydrogen halide and oxygen after which the hydrogen halide is electrically decomposed to form hydrogen. According to this method, since oxygen is obtained by a chemical reaction and hydrogen is obtained at a much lower voltage as a result of electrically decomposing hydrogen halide instead of electrically decomposing water directly, it offers the advantage of being able to reduce the amount of electrical energy required.
However, in this type of method, since carbon granules are introduced in the reaction of halogen and water, these carbon granules react with oxygen formed by the reaction in the form of a side reaction resulting in the formation of carbon dioxide. Thus, this method had the problem of low reaction efficiency as a result of the carbon granules being consumed. In order to solve this problem, the inventors of the present invention have previously proposed the use of activated carbon as catalyst in place of carbon granules in the above-mentioned reaction system (Japanese Unexamined Patent Publication No. 8-301606). As a result of using this activated carbon, reaction with oxygen is inhibited, thereby making it possible to increase the reaction efficiency.
Since activated carbon reacts less with oxygen than carbon granules, and although reaction efficiency could be improved by using activated carbon as catalyst in the reaction system of water and halogen, activated carbon still reacted to a certain extent with oxygen, thus preventing this reaction from being completely inhibited. Therefore, the inventors of the present invention searched for a catalyst that did not result in the occurrence of this type of side reaction, thereby leading to completion of the present invention.